The years 1965, 66, and 67 had only SMS (Special Mint Sets) instead of proofs. Some of these are almost indistinguishable from proofs, though. In 1969 the obverse was retooled to reverse the extreme wear on the hubs after about 50 years of use. Here is a comparison. Since the last coin I posted was 1969, the next poster may follow with any Lincoln or any coin dated 1969.